97 Civic LX, overheating and I've replaced a ton of stuff
 

Please help me solve the cooling system problem from hell

If we need all the backstory I can provide it, but heres the skinny:

Car - 1997 Honda Civic LX, 194k

Problem(s):

Car overheats no matter what kind of driving I'm doing (and i do an even amount of city/highway). If I just let it idle I don't think it will overheat. I am pretty certain it is actually overheating because the first time the radiator cap popped - I turned the heat to max and the temps came down, pulled over and refilled the radiator (took very little coolant).

Radiator fan NEVER comes on, although I can force the fan on by disconnecting the plug that goes into the thermostat housing and shorting it. Turning the interior heat to max/max fan keeps the temps normal, so I've been driving around like that for the last few weeks. Temp gauge rarely goes over normal on full heat with fan at 2, never goes over normal with full heat and fan max. If I do let the temp gauge run high, it will immediately come back to normal with full heat and max fan. Dry compression test results were 195, 191, 171, 170

Water pump - is original

Coolant - doesn't appear to be leaking according to the overflow resoiver, I've done a flush and its color appeared normal

Engine Oil - I changed it a couple of weeks ago and it was also normal color. No "chocolate milk" seen during the change, on the dipstick, or underneath the fill cap.

What's been replaced in the last 10 months:
- radiator (was cracked)
- upper radiator hose (was leaking)
- thermostat/gasket (new OEM thermostat's operation verified in boiling pot of water)
- fan temp switch (the thing in the thermostat housing that turns the fan on above 190*)

I've bled the system a few times, including with the front end on ramps trying to make sure to get all the air out. Method is always to take of the rad cap, start the car, squeeze the radiator hoses to try and get any air out at the beginning. Let it idle for 20 min or so. Sometimes I've got the interior heat on sometimes not. Fan never comes on.

Monitoring the pressure on the system: pump to 16psi, always slowly falls. Will hold out at 14-15 psi for awhile, but eventually goes below 10psi.

Is it possible this is a water pump issue? I thought maybe I have a FLOW problem with overheating but rad fan never coming on, but still doesn't account for the pressure test results when it doesn't appear I'm losing coolant.

I also wonder if its still possible I have a head gasket issue, but my uncle, who is a mechanic, said I don't have exhaust fumes in my coolant.

Any other Ideas?

Re: 97 Civic LX, overheating and I've replaced a ton of stuff
 

mine was doing almost the same thing and i had new thermostat(x2),waterpump, 1 year old headgasket. would overheat on the highway unless the heat was on full turn it off and the gauge would start climbing right away. i put another head gasket in it and its all good now the fan wouldn't come on because air is geting traped by the thermostat the sensor never gets hot enought to turn on the fan (my lower rad hose would be cold even after the gauge was almost at hot. )

Re: 97 Civic LX, overheating and I've replaced a ton of stuff
 

Headgasket is most likey blown, 2 cylinders are a lot lower than the other 2. The numbers shouldn't vary much more than about 5 PSI between cylinders.

Re: 97 Civic LX, overheating and I've replaced a ton of stuff
 

is there any link of residue under the oil cap?. a good test is with the engine cold (completely cold sitting for a couple hours) start the car and run for 30sec to 1 min and kill it. take off the radiator cap USE A TOWLE FOR YOUR HAND. it sould pour out if not u more and likely have a blown head gasket. on start up is there any kind of smoke out the exhaust a havier white color to light blue?

Re: 97 Civic LX, overheating and I've replaced a ton of stuff
 

No residue under oil cap. Running the engine for just 60 sec is enough to make the coolant pour out? why is that? it doesn't seem that 60 sec would significantly heat up the coolant enough for it to expand to the point of "pouring out." That said, the last time I pressure tested I did it on a cold engine and a small amount of coolant did spill out when I took off the radiator cap. I didn't even turn the engine on though. Will have to check on the exhaust. Maybe a little white but no blue I don't think.

Re: 97 Civic LX, overheating and I've replaced a ton of stuff
 

Exhaust gas will drive the coolant back through the cooling system and into the overflow or if the rad cap is off into the air. Depending on how the headgasket it blown it will shoot out violently just turning the engine over and go about 4 feet high.

Re: 97 Civic LX, overheating and I've replaced a ton of stuff
 

So with temps in the low 60*s yesterday, there is a small amount of mostly clear white smoke on startup. 8 inches from the tailpipe and you can't see anything, coming out of the tailpipe its clear enough that it would be hard to catch with a camera. 60 seconds in its clear and it didn't smell sweet to me.

I haven't done the 'run the engine 60 sec then turn the rad cap' test yet, but I'm confused on how to interpret the results.

If coolant pours out, that *could* mean that exhaust gases are contributing to increased pressure (and heat) in my coolant and that I have a head gasket problem, correct? If it doesn't pour out it doesn't rule out the head gasket, but it is the correct result for a normally functioning cooling system, yes?

Also, would it be a good idea to take off the radiator cap prior to doing this test? that way I've 'reset' the pressure in the system. I'm thinking it could be possible the system is already under some amount of pressure before I start the motor, so if I run it for 60 sec and then take of the rad cap I may get incorrect results. Maybe it doesn't matter?

Re: 97 Civic LX, overheating and I've replaced a ton of stuff
 

Alright, looks like I'm beating this topic to death!

Results of last test-

Before doing anything I took the radiator cap off and got a tiny bit of coolant. Put it back on, ran the engine for a minute, turned off engine and took off radiator cap. Got a small amount of fluid - for sure more than the first time, but definitely not too much... maybe a couple teaspoons worth.

Barring anything else I can check, looks like I'll be doing timing belt, water pump and head gasket next month.

Re: 97 Civic LX, overheating and I've replaced a ton of stuff
 

I hope you aren't looking for anything like magic pixie dust to fix this. It's pretty obvious your headgasket needs to be replaced.

Re: 97 Civic LX, overheating and I've replaced a ton of stuff
 

I'm not. head gasket is a big job for me and I don't want to go to all that trouble to find out it was something else that would have taken a lot less time, thats all. Next step is collecting all the stuff to do the job. Since the car has 194k I'm just gonna swap the timing belt and water pump while I'm at it.

Re: 97 Civic LX, overheating and I've replaced a ton of stuff
 

Here is what you can do to check for a blown HG, usually works pretty well. Pull each plug from each cylinder and describe what the plug looks like, ie, brandew shiny clean, brown, black, etc. Then take a flashlight and look down the sparkplug hole and see what the top of the piston looks like, ie, shiny clean, or black carbon. If any of them are "shiny clean" chances are you have a blown HG in that the coolant/water will "steam clean" the cylinder...


The other thing you can do is a coolant leak down test. You may also want to pick up some coolant dye used to diagnose blown HG, leaks, etc.

Re: 97 Civic LX, overheating and I've replaced a ton of stuff
 

HG replacement did not resolve my issue. The HG I pulled off had no cracks. Good thing I needed to replace timing belt anyway... Water pump looked brand new so isn't a water pump issue.

Even though I took it out and verified it worked I'm going to take the thermostat out of the loop completely and see if that helps.

Also, shot the bottom of my rad with an infrared temp gauge after a drive and I don't know if I got weird results or not. Started at 96* on the passenger side and stayed fairly consistent until I got all the way to the other end, where it was 107*

Shot the upper rad hose and got 205*, but the lower hose at the thermostat housing read like 120*. Wondering if, even though they both have been replaced recently, I've got a FLOW issue due to thermostat or radiator clog.

Still think I've got a leak issue too so the dye is on its way. After buttoning everything up and going for a couple of drives, I filled my coolant up to *exactly* the max line, and even now when the car is cool the coolant is at exactly the max line. Not quite sure how I've got a leak yet I'm apparently not loosing any coolant.

And lastly, when i pulled the head off I did have it checked/planed and compression tested to verify it was fine.

Re: 97 Civic LX, overheating and I've replaced a ton of stuff
 

Clogged radiator or bad thermostat?

Re: 97 Civic LX, overheating and I've replaced a ton of stuff
 

So tonight I drained the coolant out and took out the thermostat. Put everything back together and drove it around. Temps stayed normal the whole time no matter what I did, fan kicked on when I let it sit and idle.

This strikes me as quite odd considering:

1> I bought the tstat NEW, from a honda dealer
2> Before installing the tstat I suspended it in a pot of water, which I heated to boiling, and verified it opened at the right temp.

I didn't think I had to test the system with the tstat out based on the above, but apparently I was wrong! I may pickup another new tstat, but how is the system supposed to work before the tstat opens? Is "the heat" supposed to make its way all the way from the upper rad hose all the way back to the tstat with NO circulation? And when it gets hot enough the tstat finally opens?

Re: 97 Civic LX, overheating and I've replaced a ton of stuff
 

bad waterpump possible... depends how many times it been overheat BLOWN HEADGASKET

Re: 97 Civic LX, overheating and I've replaced a ton of stuff
 

When did you purchase the car?

I understand that the replace of the Head Gasket is a big project. I understand that the replace of the timing belt and the water pump is a serious project for you also, for me too.
You said the water pump is OEM, but when was the last time when it was replaced?
The Honda Manual says that you have to Inspect the Water Pump and Replace the Timing Belt every 90K miles.

1. Check for leaks and coolant smell all around the engine.

2. To check is the head gasket blown. Take off the oil filter and cut it on a have w/t some kind of saw. If the filter has inside mushy silver like residue, probably coolant along with the oil past through it - blown head gasket!

3. Check is the fan el. motor works. Probably works since you said it turned on last time.

4. Take out the radiator and flush it well with water.

5. Make sure the thermostat is installed correctly.

If everything is fine above:

6. Change the water pump.

7. Replaced the head gasket.

Re: 97 Civic LX, overheating and I've replaced a ton of stuff
 

Are you guys reading the thread?

I'd already replaced the following in the last year, and it was still overheating:

- radiator
- thermostat (with an OEM one)
- upper rad hose
- water pump (even though the one I took out looked fine)
- head gasket
- fan temp switch in the tstat housing

I'd tested the new OEM tstat in water and verified it was working. I find it hard to believe you could install one wrong unless you weren't paying any attention. Both the gasket and the tstat only fit one way and there is a notch in the gasket for proper orientation. That said, I took the tstat out and slapped everything back together and my problem was gone. Considering I tested it, I'm not absolutely certain the tstat is the root cause.

My new question is: when the engine is cold, how does the heat make it to the tstat? When my engine was cooking I checked the temp of the hose leading to the tstat and it was 150*, NOT enough for the tstat to open, even though the upper hose leading into the rad was pushing 210*. It seems like the heat of the engine never made it to the tstat, so I'm trying to figure out how the system is supposed to work when the car is cold/tstat closed.

Re: 97 Civic LX, overheating and I've replaced a ton of stuff
 

My guess is that the cooling system was not bled completely, and air was trapped there, leading to coolant flow blockage and engine overheating. During or after removal of the t-stat, the air bubbles were released.

Of course the t-stat must be reinstalled as it is needed for proper functioning of the cooling system. When you reinstall it, bleed the system:
-------------
Bleeding the cooling system may take 20-30 minutes:

1) Park the car on an inclined driveway with the front end higher than the rear.

2) Push/turn the dash heater lever/knob to MAX heat. Fan need not be on.

3) Follow the directions in the diagram below


http://i639.photobucket.com/albums/u...cture_3542.jpg

Re: 97 Civic LX, overheating and I've replaced a ton of stuff
 

*sigh* thats how I've been doing it, but right now pending a retest of the tstat its the only explanation that makes sense. Hopefully this time it works

Re: 97 Civic LX, overheating and I've replaced a ton of stuff
 

Bleed your system again as the previous guy said!

Squeeze the hoses to check if some of the them is under pressure, inflated.


As the guy wrote above - it depends how much and how many times overheated you might need new head gasket again!

I don't see a problem to take off the oil filter (it's just 15 bucks), cut it on half and inspected for what I wrote above, just to make sure you head gasket is in tack?!?

I asked when did you buy the car, bc the previous owner might had the same problem and pour into the coolant those sh*ts for clogging leaks. And that stuff may plugged some canals in the cooling path. And even if you changed the coolant once i t might not came out completely.

Re: 97 Civic LX, overheating and I've replaced a ton of stuff
 

you either didnt bleed the system completely or intalled the thermostat incorrectly, since its the thermo that acts like a valve opening and shutting off the coolant flow.

Re: 97 Civic LX, overheating and I've replaced a ton of stuff
 

Its also not super uncommon for dealer parts to be defective. I worked at a dealership last year and at least 2x a month we'd install brand new factory parts....

and we'd have to replace em. Rotors, belts, even thermos.....

Its the metals were using these days....they are crap. Alot of metal is coming thru mexico and they make crap that just WONT last.

Go to a parts store, and buy a belt that says made in mexico...and I guarantee you that in a few weeks, youll be hearing squeals.

Exhaust systems are the same. I personally saw 5 different exhaust systems that were put on (all dealer installed...all dealer parts) and 8-9 months later...all rusted to shit.

So...probably was the thermo was defected, and / or you had air in the system.

Re: 97 Civic LX, overheating and I've replaced a ton of stuff
 

The OP did mention that the t-stat was tested:

Re: 97 Civic LX, overheating and I've replaced a ton of stuff
 

well, it appears even tested OEM parts can "act differently" in a short amount of time. I tested the tstat before installing and it worked as I would expect (open @ 170*)

I tested the tstat yesterday and it didn't open until well into the 180's. So looks like another new tstat for me, although this time I'll be buying one from autozone. Frustrating that a part I bought in February crapped out so quickly.

Re: 97 Civic LX, overheating and I've replaced a ton of stuff
 

Your new OEM t-stat is fine:

http://i639.photobucket.com/albums/u...ure_6044-1.jpg